Vancomycin dosing and therapeutic drug monitoring practices: guidelines versus real-life

Recommended doses of endovenous vancomycin are insufficient to achieve therapeutic concentrations in paediatric patients

OBJECTIVES

Vancomycin therapeutic drug monitoring is challenging, especially in the paediatric population where evidence is scarce. The main objective of this study was to analyse the achievement of therapeutic concentrations of vancomycin in paediatric patients and to evaluate the current monitoring method (trough levels), doses used, and the time required to achieve target concentrations.

METHODS

Paediatric patients on treatment and monitored with vancomycin from November 2019 to December 2021 were included. Those with only one determination of serum vancomycin concentration were excluded. Demographic variables, analytical and microbiological parameters and toxicity data were collected. Pharmacokinetic parameters were assessed at baseline and during treatment.

RESULTS

225 patients (40.9% female; 108 neonates, 49 infants and 68 children or adolescents) were included in the study. The main indications for vancomycin treatment were sepsis (33.9%) and fever of unknown origin (29.3%). Microbiological cultures were positive in 71.1%, mostly with Gram-positive bacteria (60.4%). Therapeutic levels of vancomycin were reached in only 20.1% of the participants in the first determination. After pharmacokinetic monitoring, 81.7% of patients reached therapeutic concentrations, requiring a 23% increase in the initial dose, a 2-day lag time and 1-2 dosage adjustments until the therapeutic concentration was reached. Of the total patients, 13 developed nephrotoxicity, nine neutropenia and one patient developed red man syndrome.

CONCLUSIONS

In our sample of paediatric patients, the recommended doses of vancomycin were insufficient to achieve therapeutic concentrations. Revision of the recommendations and/or a change in the method of pharmacokinetic monitoring is crucial to optimise treatment in this population.

Optimizing vancomycin therapeutic drug monitoring compliance in pediatric oncology: towards personalized medication management

Aim: Vancomycin, a crucial treatment for Gram-positive bacteria, necessitates therapeutic drug monitoring (TDM) to prevent treatment failures. We investigated the healthcare professional's compliance toward TDM of vancomycin recommendations and follow-up levels. Materials & methods: We collected data from 485 patients who received vancomycin in the Children's Cancer Hospital Egypt 57357 medical records system (Cerner) over 4 months, from January to April 2020. Results: Our data shows that only 54% of patients had TDM requests from healthcare professionals for the total patients who received vancomycin treatment. The healthcare professionals' compliance with the recommendations was 91.7%, while the follow-up levels were 66.7%. Conclusion: While overall adherence to recommendations is strong, enhancing compliance with follow-up levels remains a priority for improvement.

Optimizing vancomycin dosing in pediatrics: a machine learning approach to predict trough concentrations in children under four years of age

BACKGROUND

Vancomycin trough concentration is closely associated with clinical efficacy and toxicity. Predicting vancomycin trough concentrations in pediatric patients is challenging due to significant inter-individual variability and rapid physiological changes during maturation.

AIM

This study aimed to develop a machine learning model to predict vancomycin trough concentrations and determine optimal dosing regimens for pediatric patients < 4 years of age using ML algorithms.

METHOD

A single-center retrospective observational study was conducted from January 2017 to March 2020. Pediatric patients who received intravenous vancomycin and underwent therapeutic drug monitoring were enrolled. Seven ML models [linear regression, gradient boosted decision trees, support vector machine, decision tree, random forest, Bagging, and extreme gradient boosting (XGBoost)] were developed using 31 variables. Performance metrics including R-squared (R2), mean square error (MSE), root mean square error (RMSE), and mean absolute error (MAE) were compared, and important features were ranked.

RESULTS

The study included 120 eligible trough concentration measurements from 112 patients. Of these, 84 measurements were used for training and 36 for testing. Among the seven algorithms tested, XGBoost showed the best performance, with a low prediction error and high goodness of fit (MAE = 2.55, RMSE = 4.13, MSE = 17.12, and R2 = 0.59). Blood urea nitrogen, serum creatinine, and creatinine clearance rate were identified as the most important predictors of vancomycin trough concentration.

CONCLUSION

An XGBoost ML model was developed to predict vancomycin trough concentrations and aid in drug treatment predictions as a decision-support technology.

Evaluation of Real-World Vancomycin Dosing and Attainment of Therapeutic Drug Monitoring Targets

In 2020, the Infectious Diseases Society of America (IDSA) recommended a change in vancomycin therapeutic drug monitoring from trough-based to AUC/MIC-based to optimize vancomycin's efficacy and reduce nephrotoxicity. Many hospitals have not implemented this change due to barriers such as the cost of AUC/MIC software and lack of provider familiarity. The purpose of this study was to determine the rate of AUC/MIC ratio target attainment using current trough-based vancomycin dosing practices at a city hospital. The rates of acute kidney injury (AKI) were also evaluated. Vancomycin orders were reviewed retrospectively to determine the expected AUC/MIC ratios using first-order pharmacokinetic equations over a 7-month period. Orders were excluded if they were written for a one-time dose, for individuals less than 18 years of age, or for those on hemodialysis. A total of 305 vancomycin orders were included in this review. Overall, 27.9% (85/305) of vancomycin orders attained the AUC/MIC ratio target of 400-600 mg·h/L as recommended by the guidelines. Nearly 35% (106/305) achieved AUC/MIC ratios below 400 mg·h/L and 37.4% (114/305) achieved AUC/MIC ratios above 600 mg·h/L. Orders for obese patients were significantly more likely to have below the target AUC/MIC ratios (68% vs. 23.9%, X² 48.48, p < 0.00001) and non-obese patients were significantly more likely to have above the target AUC/MIC ratios (45.7% vs. 12%, X² 27.36, p < 0.00001). The overall rate of acute kidney injury observed was 2.6%. Most vancomycin orders did not attain therapeutic drug monitoring targets, reflecting the ongoing clinical challenge of optimizing vancomycin doses and implementing new guideline recommendations.

Awareness, perception, and barriers of healthcare providers toward the revised consensus guideline for therapeutic monitoring of vancomycin

Background

A revised consensus guideline published in 2020 recommended transitioning vancomycin monitoring to the area under the concentration-time curve over 24 h to minimum inhibitory concentration (AUC₂₄/MIC). The decision to transition to AUC₂₄/MIC monitoring or to continue trough-based monitoring is made at the institutional level and is influenced by several factors, including healthcare providers and system-related factors. Changing current practices is expected to be difficult, and it is important to understand healthcare providers' perceptions and potential barriers before the transition. This study assessed the awareness and perception of physicians and pharmacists toward the revised guideline and identified barriers to their implementation in Kuwait.

Methods

A cross-sectional survey that employed a self-administered questionnaire was used. A random sample of physicians (n = 390), clinical microbiologists (n = 37), and clinical pharmacists (n = 48) across six Kuwaiti public hospitals were surveyed. Descriptive and comparative statistical analyses were performed. Factors associated with awareness and perceptions among the participants were identified.

Results

The response rate was 85.3% (n = 431). Participants had a high (median = 75%) awareness score for the updated vancomycin guideline, as well as a positive perception (median = 5). The main factor identified to affect the awareness and perception of participants following the group analysis was the years of experience. The main barriers identified were a lack of training to perform vancomycin AUC₂₄ calculations, a lack of accurate documentation sample time, and a long turnaround time for serum levels, which might hinder the implementation of the updated guideline.

Conclusion

Physicians, clinical microbiologists, and pharmacists working in Kuwait public hospitals were aware of the 2020 vancomycin monitoring guidelines with positive perceptions. Participants agreed on the several barriers to transitioning to the AUC₂₄/MIC approach, which should be considered by stakeholders before implementation.

Altered Pharmacokinetics Parameters of Vancomycin in Patients with Hematological Malignancy with Febrile Neutropenia, a Bayesian Software Estimation

The pharmacokinetics of vancomycin vary significantly between specific groups of patients, such as critically ill patients and patients with hematological malignancy (HM) with febrile neutropenia (FN). Recent evidence suggests that the use of the usual standard dose of antibiotics in patients with FN may not offer adequate exposure due to pharmacokinetic variability (PK). Therefore, the purpose of this study is to assess the effect of FN on AUC_0-24 as a key parameter for vancomycin monitoring, as well as to determine which vancomycin PK parameters are affected by the presence of FN using Bayesian software PrecisePK in HM with FN. This study was carried out in King Abdulaziz Medical City. All adult patients who were admitted to the Princess Norah Oncology Center PNOC between 1 January and 2017 and 31 December 2020, hospitalized and received vancomycin with a steady-state trough concentration measured before the fourth dose, were included. During the trial period, 297 patients received vancomycin during their stay at the oncology center, 217 of them meeting the inclusion criteria. Pharmacokinetic parameters were estimated for the neutropenic and non-FN patients using the precise PK Bayesian platform. The result showed that there was a significant difference (p < 0.05) in vancomycin clearance Cl_van, the volume of distribution at a steady-state V_dss, the volume of distribution for peripheral compartment V_dp, half-life for the elimination phase t½_β, and the first-order rate constant for the elimination process β in FN compared to non-FN patients. Furthermore, AUC_0-24 was lower for FN patients compared to non-FN patients, p < 0.05. FN has a significant effect on the PK parameters of vancomycin and AUC_0-24, which may require specific consideration during the treatment initiation.

Comparison of Intravenous Microdialysis and Standard Plasma Sampling for Monitoring of Vancomycin and Meropenem Plasma Concentrations-An Experimental Porcine Study

Microdialysis is a catheter-based method suitable for dynamic sampling of unbound antibiotic concentrations. Intravenous antibiotic concentration sampling by microdialysis has several advantages and may be a superior alternative to standard plasma sampling. We aimed to compare concentrations obtained by continuous intravenous microdialysis sampling and by standard plasma sampling of both vancomycin and meropenem in a porcine model. Eight female pigs received 1 g of both vancomycin and meropenem, simultaneously over 100 and 10 min, respectively. Prior to drug infusion, an intravenous microdialysis catheter was placed in the subclavian vein. Microdialysates were collected for 8 h. From a central venous catheter, plasma samples were collected in the middle of every dialysate sampling interval. A higher area under the concentration/time curve and peak drug concentration were found in standard plasma samples compared to intravenous microdialysis samples, for both vancomycin and meropenem. Both vancomycin and meropenem concentrations obtained with intravenous microdialysis were generally lower than from standard plasma sampling. The differences in key pharmacokinetic parameters between the two sampling techniques underline the importance of further investigations to find the most suitable and reliable method for continuous intravenous antibiotic concentration sampling.

Vancomycin efficiency and safety of a dosage of 40–60 mg/kg/d and corresponding trough concentrations in children with Gram-positive bacterial sepsis

Background

Optimal vancomycin trough concentrations and dosages remain controversial in sepsis children. We aim to investigate vancomycin treatment outcomes with a dosage of 40-60 mg/kg/d and corresponding trough concentrations in children with Gram-positive bacterial sepsis from a clinical perspective.

Methods

Children diagnosed with Gram-positive bacterial sepsis and received intravenous vancomycin therapy between January 2017 and June 2020 were enrolled retrospectively. Patients were categorized as success and failure groups according to treatment outcomes. Laboratory, microbiological, and clinical data were collected. The risk factors for treatment failure were analyzed by logistic regression.

Results

In total, 186 children were included, of whom 167 (89.8%) were enrolled in the success group and 19 (10.2%) in the failure group. The initial and mean vancomycin daily doses in failure group were significantly higher than those in success group [56.9 (IQR =42.1-60.0) vs. 40.5 (IQR =40.0-57.1), P=0.016; 57.0 (IQR =45.8-60.0) vs. 50.0 (IQR =40.0-57.6) mg/kg/d, P=0.012, respectively] and median vancomycin trough concentrations were similar between two groups [6.9 (4.0-12.1) vs.7.3 (4.5-10.6) mg/L, P=0.568)]. Moreover, there was no significant differences in treatment success rate between vancomycin trough concentrations ≤15 mg/L and &gt;15 mg/L (91.2% vs. 75.0%, P=0.064). No vancomycin-related nephrotoxicity adverse effects occurred among all enrolled patients. Multivariate analysis revealed that a PRISM III score ≥10 (OR =15.011; 95% CI: 3.937-57.230; P&lt;0.001) was the only independent clinical factor associated with increased incidence of treatment failure.

Conclusions

Vancomycin dosages of 40-60 mg/kg/d are effective and have no vancomycin-related nephrotoxicity adverse effects in children with Gram-positive bacterial sepsis. Vancomycin trough concentrations &gt;15 mg/L are not an essential target for these Gram-positive bacterial sepsis patients. PRISM III scores ≥10 may serve as an independent risk factor for vancomycin treatment failure in these patients.

Artificial Intelligence in Pediatric Nephrology-A Call for Action

Artificial intelligence is playing an increasingly important role in many fields of clinical care to assist health care providers in patient management. In adult-focused nephrology, artificial intelligence is beginning to be used to improve clinical care, hemodialysis prescriptions, and follow-up of transplant recipients. This article provides an overview of medical artificial intelligence applications relevant to pediatric nephrology. We describe the core concepts of artificial intelligence and machine learning and cover the basics of neural networks and deep learning. We also discuss some examples for clinical applications of artificial intelligence in pediatric nephrology, including neonatal kidney function, early recognition of acute kidney injury, renally cleared drug dosing, intrapatient variability, urinary tract infection workup in infancy, and longitudinal disease progression. Furthermore, we consider the future of artificial intelligence in clinical pediatric nephrology and its potential impact on medical practice and address the ethical issues artificial intelligence raises in terms of clinical decision-making, health care provider-patient relationship, patient privacy, and data collection. This article also represents a call for action involving those of us striving to provide optimal services for children, adolescents, and young adults with chronic conditions.

Evaluation of vancomycin pharmacokinetics in patients with augmented renal clearances: A randomized clinical trial

Purpose: Vancomycin is a narrow therapeutic window glycopeptide antibiotic that acts against Gram-positive bacteria. As it is renally eliminated, therapeutic drug monitoring is recommended for vancomycin, especially in case of kidney function alteration. Augmented renal clearance (ARC), defined as a creatinine clearance of more than 130 ml/min, is a risk factor for sub-therapeutic concentrations of vancomycin. This study aimed to evaluate the vancomycin pharmacokinetics following the administration of two different regimens in ARC patients.

Methods: A randomized clinical trial (IRCT20180802040665N1) was conducted on patients in need of vancomycin therapy. Eight hours of urine was collected and 56 patients divided into two groups with creatinine clearance of more than 130 ml/min were included in the study. The first group received 15 mg/kg of vancomycin every 12 h and the second group 15 mg/kg every 8 h. After four doses, the peak and trough concentrations were measured from two blood samples. The primary outcome was the percentage of patients who attainted AUC more than 400. The occurrence of acute kidney injury also was evaluated after seven days.

Results: The mean age of patients in the every 12 h and every 8 h groups was 44.04 ± 16.55 and 42.86 ± 11.83 years, respectively. While neurosurgical issues were the most common causes of hospitalization, central nervous infections were the most common indications for vancomycin initiation. Urinary creatinine clearance was 166.94 ± 41.32 ml/min in the every 12 h group and 171.78 ± 48.56 ml/min in the every 8 h group. 46.42% of patients in the every 12 h group and 82.14% of patients in the every 8 h group attained AUC/MIC of more than 400 mg × hr/L. None of the patients in the every 12 h group reached more than 15 mcg/ml concentration. At the 7-day follow-up, 10.7% patients in the BD group and 28.6% patients in the TDS group developed acute kidney injury (p = 0.089).

Conclusion: Administration of vancomycin at a dose of 15 mg/kg every 8 h is associated with higher pharmacokinetic attainment in ARC patients. The occurrence of acute kidney injury also was not significantly higher in this therapeutic regimen. AUC/MIC monitoring is necessary in this population.

An Audit to Evaluate Vancomycin Therapeutic Drug Monitoring in a Neonatal Intensive Care Unit

BACKGROUND

Therapeutic drug monitoring (TDM) is routinely used for optimization of vancomycin therapy, because of exposure-related efficacy and toxicity, in addition to significant variability in pharmacokinetics, which leads to unpredictable drug exposure.

OBJECTIVE

The aim of this study was to evaluate target attainment and TDM of vancomycin in neonates.

METHODS

The authors conducted a retrospective study and collected data from medical records of all neonates who received vancomycin therapy in the neonatal intensive care unit between January 2019 and December 2019. The primary outcome was the proportion of vancomycin courses that reached target trough concentrations of 10-20 mg/L based on appropriate TDM samples collection. Secondary outcomes included proportion of courses with appropriate dose and dose frequency, and proportion of patients who achieved target concentrations after the first dose adjustment.

RESULTS

In total, 69 patients were included, with 129 vancomycin courses. The median initial vancomycin trough concentration was 12 (range: 4-36) mg/L. The target trough concentration was achieved in 75% of courses after the initial dose with appropriate TDM, and 84% of courses after TDM-guided dose adjustments. Patients were dosed appropriately in 121/129 courses and TDM was performed correctly according to protocol in 51/93 courses. A dose adjustment was performed in 18/29 courses, to increase target attainment.

CONCLUSIONS

This study showed that there is a need for an increase in dose to improve target attainment. There is also a need to explore more effective TDM strategies to increase the proportion of neonatal patients attaining vancomycin target trough concentrations.

Vancomycin therapeutic drug monitoring in patients on continuous renal replacement therapy: a retrospective study

Objectives

This study aimed to investigate vancomycin therapeutic drug monitoring (TDM) in patients on continuous renal replacement therapy (CRRT) and explore the risk factors for exceeding the target concentration.

Methods

This retrospective study enrolled patients aged ≥18 years who were admitted to the intensive care unit and treated with ≥3 intravenous vancomycin doses during CRRT, and who underwent vancomycin TDM. Demographic and other information were collected. Multivariate logistic regression was used assess the risk factors for exceeding the target concentration.

Results

Sixty-nine patients were included, and 40.6% patients underwent TDM. Additionally, 14.5% of patients reached the optimal concentration, and 87.5% of patients who exceeded the target received a daily dose adjustment. The cumulative dose of vancomycin and serum albumin were risk factors for exceeding the target concentration in patients on CRRT.

Conclusions

Patients on CRRT did not meet the optimal vancomycin management; <50% of the patients routinely received vancomycin TDM, and <15% achieved the optimal concentration. Fewer patients in the subtherapeutic group received a daily dose adjustment than those who exceeded the target concentration. Cumulative vancomycin and serum albumin doses before TDM were the risk factors for exceeding the target concentration in CRRT patients.

Continuous infusion versus intermittent infusion of vancomycin in critically ill patients undergoing continuous venovenous hemofiltration: a prospective interventional study

BACKGROUND

A prospective interventional study comparing outcomes in critically ill patients receiving intermittent infusion (II) or continuous infusion (CI) of vancomycin during continuous venovenous hemofiltration (CVVH) is lacking. The objective of this study was to compare the pharmacokinetic/pharmacodynamics (PK/PD) target attainment, therapeutic efficacy and safety among critically ill patients who received CI or II of vancomycin in a prospective interventional trial and to explore the correlations of effluent flow rate (EFR) with PK/PD indices.

METHODS

This prospective interventional study was conducted in two independent intensive care units (ICUs) from February 2021 to January 2022. Patients in one ICU were assigned to receive CI (intervention group) of vancomycin, whereas patients in the other ICU were assigned to receive II regimen (control group). The primary outcome was to compare the PK/PD target attainment, including target concentration and target area under the curve over 24 h to minimum inhibitory concentration (AUC₂₄/MIC).

RESULTS

Overall target attainment of PK/PD indices was higher with CI compared with II, irrespective of target concentration (78.7% vs. 40.5%; P < 0.05) or AUC₂₄/MIC (53.2% vs. 28.6%; P < 0.05). There were no significant differences in clinical success (72.2% vs. 50.0%; P = 0.183) and microbiological success (83.3% vs. 75.0%, P = 0.681) between the patients treated with CI or II of vancomycin. Adverse reactions occurred at similar rates (0.0% vs. 4.4%; P = 0.462), and mortality between the two modalities was also not significant different (21.7% vs. 17.9%; P = 0.728). Correlation analysis showed a weak to moderately inverse correlation of EFR with observed concentration (r = - 0.3921, P = 0.01) and AUC₂₄/MIC (r = - 0.3811, P = 0.013) in the II group, whereas the correlation between EFR and observed concentration (r = - 0.5711, P < 0.001) or AUC₂₄/MIC (r = - 0.5458, P < 0.001) in the CI group was stronger.

CONCLUSION

As compared to II, CI of vancomycin in critically ill patients undergoing CVVH was associated with improved attainment of PK/PD indices. Furthermore, the inverse correlation of PK/PD indices with EFR was stronger among patients treated with CI of vancomycin. Trial registration The trial was registered in the Chinese clinical trial registration center (21/01/2021-No. ChiCTR2100042393).

Systematic Comparison of Hospital-Wide Standard and Model-Based Therapeutic Drug Monitoring of Vancomycin in Adults

We aimed to evaluate the predictive performance and predicted doses of a single-model approach or several multi-model approaches compared with the standard therapeutic drug monitoring (TDM)-based vancomycin dosing. We performed a hospital-wide monocentric retrospective study in adult patients treated with either intermittent or continuous vancomycin infusions. Each patient provided two randomly selected pairs of two consecutive vancomycin concentrations. A web-based precision dosing software, TDMx, was used to evaluate the model-based approaches. In total, 154 patients contributed 308 pairs. With standard TDM-based dosing, only 48.1% (148/308) of all of the second concentrations were within the therapeutic range. Across the model-based approaches we investigated, the mean relative bias and relative root mean square error varied from −5.36% to 3.18% and from 24.8% to 28.1%, respectively. The model averaging approach according to the squared prediction errors showed an acceptable bias and was the most precise. According to this approach, the median (interquartile range) differences between the model-predicted and prescribed doses, expressed as mg every 12 h, were 113 [−69; 427] mg, −70 [−208; 120], mg and 40 [−84; 197] mg in the case of subtherapeutic, supratherapeutic, and therapeutic exposure at the second concentration, respectively. These dose differences, along with poor target attainment, suggest a large window of opportunity for the model-based TDM compared with the standard TDM-based vancomycin dosing. Implementation studies of model-based TDM in routine care are warranted.

[Therapeutic drug monitoring and pharmacokinetic models as a strategy for rational antibiotic therapy in intensive care patients]

BACKGROUND AND OBJECTIVE

Antibiotic dosing in intensive care patients is complex due to pharmacokinetic (PK) alterations. The aim of this article is to illustrate the role of therapeutic drug monitoring (TDM) and PK models to individualize antibiotic dosing.

MATERIAL AND METHODS

Guidelines and recommendations are discussed in the context of clinical practice and the prerequisites for routine TDM of different antibiotics are presented. In addition, the benefits and limitations of TDM are discussed. The advantages and disadvantages of TDM and PK models are described and the resulting future options are presented.

RESULTS

In the clinical routine, the peak or trough concentrations of antibiotics in blood are measured depending on the antibiotic class. Prerequisites for a purposeful TDM are a coordinated blood sampling and a prompt reporting of findings. As target ranges are not uniformly defined following rules, dosage adjustments are difficult. The PK models offer a valid possibility to individualize the antibiotic therapy of intensive care patients. Areas of application are the calculation of the loading dose and the combination with TDM for treatment control. For whom and how often TDM is necessary and how it can best be combined with PK models or even replace them should be investigated in the future, in addition to evaluation of the optimal target area.

CONCLUSION

The routine use of TDM for antibiotics in intensive care patients is only effective under the abovementioned conditions. By combination with PK models the treatment could be optimized in the future.

Therapeutic drug monitoring of vancomycin in neurosurgery patients, from trough concentration to area under the curve: a retrospective single center cohort study in a tertiary hospital

OBJECTIVE

To evaluate the effect of therapeutic drug monitoring (TDM) of vancomycin in neurosurgery patients.

METHODS

In this retrospective, single-center cohort study, data were collected from patients administered vancomycin after neurosurgery during 2020. Intervention by a pharmacist using an area under the curve (AUC)-based strategy for TDM of vancomycin was started on 1 July 2020. The trough concentration was monitored previously. Data regarding basic demographics, vancomycin application, and TDM were collected and analyzed.

RESULTS

Ninety and 155 samples were included in the non-intervention and intervention groups, respectively. No difference in baseline characteristics was detected. After intervention, the attainment rate of vancomycin TDM was significantly increased from 36.7% to 52.3%. The intervention resulted in an increased daily vancomycin dose (28.9 vs. 26.7 mg/kg/day), a more reasonable sample extraction time (sixth vs. ninth dose), reductions in dose adjustments (37.4% vs. 54.4%) and preventative applications (66.7% vs. 52.3%), and no difference in kidney function impact. The intervention group had a shorter hospital stay.

CONCLUSIONS

Intervention by a clinical pharmacist using an AUC-based strategy for vancomycin TDM can provide benefits other than pharmacokinetic attainment in neurosurgery patients. Further prospective multi-center studies are needed to establish standardized intervention measures and evaluation indicators.

Variation in vancomycin dosing and therapeutic drug monitoring practices in neonatal intensive care units

Background Vancomycin is a frequently used antibiotic in neonates. However, there is no consensus guideline on the optimal dosing regimen and therapeutic drug monitoring (TDM) practices in this patient population. Objective To document the variability in the current dosing and TDM practices in neonatal intensive care units (NICU). Setting Belgian and Dutch NICUs. Method An online questionnaire was disseminated by e-mail to potential respondents. Main outcome measure Differences in vancomycin dosing and TDM practices in comparison with a reference source, the Dutch Paediatric Formulary. Results Eighteen NICUs (response rate 62%) participated. Eleven different dosing regimens are applied, with 83% using intermittent dosing regimens. Stratifying covariates used to determine the (initial) dosage include gestational age, postnatal age, serum creatinine, concurrent use of non-steroidal anti-inflammatory drugs, birth weight and current weight. Large variability is observed with regard to TDM practice as well, both for the concentration target range and the times of (re)sampling. Dosing calculators are more commonly used in the Netherlands than Belgium. Conclusion Significant inter-centre variability in dosing and TDM practices was found. The development of international consensus guidelines is required to optimize therapy. Dosing calculators to guide dosing are not yet considered as part of standard-of-care.